A case-control study designed to evaluate the relationship between endometrial cancer risk and obesity pattern is planned. It is hypothesized that women with upper body segment obesity (UBSO, android obesity) experience an appreciably higher risk of endometrial cancer than do nonobese women. It is also hypothesized that women with lower body segment obesity (LBSO, gynecoid obesity) experience an endometrial cancer risk intermediate to that of UBSO women and the nonobese. The proposed study will also evaluate the overall relationship between obesity, as measured by skinfolds, and endometrial cancer risk. Two hundred women with newly diagnosed endometrial carcinoma and 400 hospital controls will be enrolled during a three year period. Anthropometric measurements (skinfolds and circumferences) will be obtained from subjects and these measurements will be used to classify women according to obesity pattern. A short interview will also be obtained which will elicit information about the subjects' history of exposure to other putative determinants of endometrial cancer. A blood sample will also be obtained from postmenopausal subjects. Serum estradiol 17 Beta, estrone, and androstenedione levels will be determined by radioimmunoassay. It is hypothesized that UBSO postmenopausal women will have higher serum estrogen levels, particularly estrone, than will LBSO postmenopausal women. This may be so because fundamental metabolic differences between fat cells of UBSO and LBSO have been reported and the major source of estrone among postmenopausal women is the conversion of plasma androstenedione to estrone by adipose tissue. The relationship between serum hormonal levels and obesity pattern will be evaluated among the controls. The inclusion of serum hormonal assays on the cases will enable an evaluation of the joint effects of obesity pattern and estrone levels on endometrial cancer risk. The observations that UBSO women are at higher risk of endometrial cancer than are LBSO women and that UBSO is related to higher endogenous estrone levels would considerably enhance our understanding of the hormonal etiology of endometrial cancer; a common malignancy among postmenopausal women.